JPH02162279A - Magnetoresistance element and preparation thereof - Google Patents

Abstract

PURPOSE:To use a reluctance element in element arrangement receiving no adverse effect due to the mold protrusion of a terminal part by allowing a sensor part composed of a thin film to protrude to the other part on a pellet constituting the element. CONSTITUTION:A sensor part is formed from an insulating substrate, a baked film 2 composed of an insulating material and a ferromagnetic thin film 3. Further, terminal electrode parts 4A-4C are provided and the thin film 3 containing the sensor part is covered with a protective film 5. It is necessary to bring the surface of the baked film 2 to a mirror surface state extremely reduced in unevenness and, pref., it is necessary to set said surface to surface roughness of 100Angstrom or less. Further, it is necessary that the difference in level of the substrate 1 with the surface of the baked film 2 is set to at least 20mum because output is extremely lowered when a molding surface protrudes by 100mum or less from the surface of the baked film 2 at the time of the application of molding to a terminal part. A material excellent in heat resistance is required as the substrate 1 and, when the temp. at the time of the formation of the baked film or at the time of welding is considered, a material stable up to at least 400 deg.C is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive element made of a highly sensitive ferromagnetic thin film and a method for manufacturing the same.

[Conventional technology] The present inventors have already published JP-A-62-128578.

JP-A No. 62-131589 and JP-A-Sho [i3-
No. 170981 proposes a technology for a ferromagnetic thin film magnetoresistive element. FIG. 9(^) shows a top view of the example, and FIG. 9(B) shows a sectional view taken along line A--A. In this conventional example, a three-terminal sensor section is formed using a ferromagnetic thin film 3 on an insulating substrate 1. 5 is a protective film, 7 is a lead wire, and 8 is a resin coating layer. In these conventional techniques, as shown in FIGS. 9(^) and (B), the electrode of the lead 7, that is, the terminal part,
Basically, the sensor element section that detects the magnetic field is formed on the same plane. When a magnetoresistive element having such a structure is used as a speed detection element for a DC motor, it is basically used in an arrangement as shown in FIG. 10. In this case, the magnetized ring 11 becomes a magnetic signal source, and the magnetic field strength becomes weaker as the magnetized pitch becomes finer. In recent years, motors have become smaller and more precise, and their magnetization pitches have become finer. Therefore, it is necessary to make the gap between the magnetic signal source and the sensor section of the element 13 very narrow, for example, about 100 μI. . However, in the conventional device 13 as shown in FIG. 9, the terminal portion 14 for taking out the lead is usually bonded by soldering or a similar method, and the bonding portion is covered with resin for reinforcement. It has a molded structure. That is, the bonding and mold parts protrude beyond the sensor surface. Therefore, in the past, the entire element including this mold part was used as a magnetic signal source.
1, there was a problem in that the sensor section could not be brought sufficiently close to the magnetic signal as shown in FIG. 1, and therefore a sufficient output could not be obtained. This problem is especially serious when trying to detect angular velocity with high precision using a small motor. In addition, in order to prevent the output from decreasing, there is a method of forming the terminal part 14 at a position distant from the sensor part so that the sensor part can be brought close to the magnetic signal. As shown in the figure, in this case, it is not possible to reduce the size of the element 15, and when arranging the element to face the magnetic signal source, the thickness t of the signal source
As a result, problems such as the inability to reduce the size and thickness of the motor have arisen. especially,
Miniaturization of magnetoresistive elements not only reduces element cost, but also
This leads to the miniaturization of the system including this. Therefore,
Miniaturization of devices has been a long-standing challenge.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems as explained above,
A ferromagnetic thin film with a structure that can be used in an element arrangement that does not have the adverse effects of mold protrusion on the terminal part, that is, the lead extraction part does not interfere with the detection of magnetic signals or become an obstacle to miniaturization of elements and motors. An object of the present invention is to provide a magnetoresistive element and a manufacturing method thereof.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a magnetoresistive element that uses a thin film of ferromagnetic material as a magnetic sensor part, in which the sensor part made of the thin film is It is characterized by protruding from other parts on the constituent pellets.

The method of the present invention allows for the formation of protrusions with a height of at least 20 μm.
The method is characterized in that it includes a step of depositing a ferromagnetic thin film on an insulating substrate having more than a force area.

[Function] The magnetoresistive element of the present invention has a structure in which only the sensor portion protrudes above the element substrate surface, and the terminal portion for lead extraction is formed at a position lower than the sensor surface. Therefore, when molding is performed for the purpose of reinforcing the bonding portion, the mold surface can be formed at the same level as the sensor surface. Furthermore, the device can be mass-produced without significantly changing the conventional manufacturing process, that is, without increasing the process cost, and the basic characteristics of the device are the same as those of the conventional device even if the device is miniaturized.

Furthermore, in actual use, the device structure allows the device to be placed in a position where its characteristics can be maximized compared to conventional devices.

According to the present invention, a magnetoresistive element made of a ferromagnetic thin film can be miniaturized, and even if the element is miniaturized, it is possible to detect a magnetic field at an optimal position for use with respect to a magnetic signal source.

[Example] The present invention will be explained below with reference to the drawings.

FIG. 1(^) is a top view of an embodiment of the magnetoresistive element of the present invention, and FIG. 1([I) is a sectional view taken along the line ^-^ of FIG. 1(A). This example shows an example of a three-terminal element, which is the same as the conventional example shown in FIG.

In FIGS. 1(^) and (B), 1 is an insulating substrate, 2 is a fired film made of an insulating material, and 3 is a ferromagnetic thin film.
It forms a sensor section. 4^, 4B, and 4C are terminal electrode portions for external connection. The ferromagnetic thin film including the sensor section is covered with a protective film 5. FIG. 1 shows the structure of the element pellet, and illustrations of leads and molding resin are omitted.

FIG. 2 shows a cross-sectional view of the device in the embodiment of the present invention in which the terminal electrode 4 and the lead 7 are connected via the solder 6. The vicinity of the lead connection portion is covered with resin 8. Further, FIG. 3 shows a cross-sectional structure when the terminal electrode 4 and the lead 7 are connected via the wire 9 in the embodiment of the present invention, and the element pellet is connected to the resin 8.
The structure is covered with

Normally, the sensor part of a magnetoresistive element is formed with a very thin film of 1000 Å or less, so the surface of the fired 11!20 must have a mirror-like state with very few irregularities, and preferably 1000 Å or less.
It is necessary to have a surface roughness of 0 Å or less. The fired part may be formed by applying glass powder or paste to the required area and sintering it by a method such as screen printing, or by fusing glass chips to the required area, or by flattening the fired film. In some cases, the surface is polished after firing to give it a mirror finish. The level difference between the surface of the substrate 1 and the fired film 2 should be at least 20 μm, because when molding the terminal part, if the mold surface protrudes more than 100 μm from the fired film surface, the output will be extremely low as described above. A height difference of 50 μm is required, and the height difference is preferably 50 μm.
That's all. However, if the step is too large, the subsequent photolithography process will be difficult, so the step should be 300 μm.
■The following are desirable. Further, the substrate 1 needs to be made of a material with excellent heat resistance. Considering the temperature at the time of forming the fired film or the temperature at the time of fusing, etc., it is preferable to use a material that is stable up to at least 400°C. Therefore, the substrate 1 is an insulating substrate that is generally used as a substrate for semiconductor elements. However, particularly preferred materials include a ceramic substrate, a glass substrate, a sapphire substrate, and a silicon substrate with an oxide film.

In addition to the methods described above, methods for creating a step between the sensor section and the terminal section include adding a step to the board by mechanical processing, or pressing and sintering a board with a step from the beginning. In this case as well, the surface on which the sensor part is formed needs to be mirror-finished, and for that purpose, the part where the sensor part is formed or the entire surface of the substrate is coated with 5i02 or the like. In some cases.

FIG. 4 shows a cross-sectional view of a magnetoresistive element using a substrate 1O with a step formed by machining.

In FIG. 5, the element 12 of the present invention is connected to a ring-shaped magnetic signal source 1.
This figure shows what it looks like when facing 1.

Since the element 12 is formed so that the mold surface 12^ is located at almost the same position as the sensor surface 12B, the sensor section may be too far away from the magnetic signal source as in the conventional example shown in FIG.
Unlike the conventional example shown in the figure, there is no need to place a molded part under the magnetic signal source, and furthermore, the element can be made thinner than the thickness of the ring that serves as the magnetic signal source.

Table 1 shows a comparison with the conventional example regarding the element pellet shape, shape, and number of elements that can be obtained from a 3-inch square substrate when designed to have the same resistance value and sensitivity.

Table 1 When the element of the present invention is designed to have the same resistance and sensitivity as the conventional element, the number of elements can be approximately three times as large with the same substrate area.

Next, regarding the manufacturing method of the magnetoresistive element of the present invention, FIG.
An example will be described with reference to FIGS. 7 and 8. 6th
The figure is an example of a process diagram, FIG. 7 is a top view of the element in each step, and FIG. 8 is a cross-sectional view taken along the line B in FIG. 7.

In this example, the glass fusing step in FIG. 6 is a step of fusing the glass chip 2 to an insulating substrate 1 and providing a protrusion on a part of the substrate. The condition of the board after this process is shown in the seventh figure.
Shown in Figure (^) and Figure 8 (^).

Next is an element pattern forming step. This is a process in which a thin ferromagnetic material 11j3 is deposited on a substrate and then an element pattern is formed by etching. Through this step, the device becomes in the state shown in FIG. 7 (B) and FIG. 8 (B).

The protective film forming step is a step of depositing and forming a protective film on a required portion of the element. Thereafter, a terminal electrode forming step follows.

Subsequently, processes such as cutting by dicing, bonding, and molding, which are carried out in ordinary semiconductor electronic parts, are carried out, and the manufacture of the magnetoresistive element of the present invention is completed.

Manufacturing example 1 A 3-inch square alumina ceramic substrate with a thickness of 0.25 mm and a size of 1 ml 1 x 1.5 is placed on the part where the sensor part is formed.
Glass chips measuring mm square and having mirror surfaces were fused at 550°C. Next, the entire substrate was heated and held at 300°C, and the thickness was 50°C.
An 81kNi-19XFe alloy thin film was formed by sputtering. Next, using the photoresist as an etching mask and using a cupric chloride-based etching solution, the etching process shown in FIG.
) A sensor pattern was formed as shown in (). Next, 1 μl of 5in2 film was deposited on the entire surface of the substrate by PCVD.
Next, in order to form terminal electrodes, 5i02 windows were opened at the required locations, a U film was laminated on the opened areas, and an element pellet as shown in Figure 1 was placed on a 3 inch square substrate.
It was formed at about 2000 deflections.

This board was cut into 1.2++a+ x using a dicing saw.
It was cut into element chips of 1, 1 laa+. After solder-bonding three lead wires to each element chip, epoxy resin is applied and hardened to form the magnet of the present invention, which has a cross-sectional structure in which the sensor part and the upper surface of the mold are on the same plane as shown in FIG. A resistive element was manufactured.

Table 2 shows the device characteristics. For comparison, the values of the conventional example are shown at the same time, and although the element chip area of the present example is approximately 173 times larger than that of the conventional example, the same resistance value and sensitivity are obtained.

Table 2 Manufacturing Example 2 Apply glass paste to a thickness of 0.05 mm and 1 mm by screen printing on a 3-inch square alumina ceramic substrate.
It was applied to a pattern of x 1.5 mm square and baked at about 600°C. Next, surface polishing was performed to reduce the surface roughness of the fired glass surface to 100 Å or less. Next, heat the entire board to 300°C.
Heated and held to 81 thickness of 500 people! kNi-19*F
An e-alloy thin film was formed by sputtering. Hereinafter, production example 1
A magnetoresistive element of the present invention was manufactured in the same manner as described above. The characteristics of the obtained device were similar to those of the device shown in Production Example 1.

Production Example 3 A 3-inch square glass substrate with a mirror-like surface and a thickness of 0.6m+a was heated to a depth of 0.2111mm using a diamond plate.
A groove of 111 was processed, and a protruding portion of In+m x +, 5 aun angle was provided at a portion where a sensor portion would later be formed. Next, the entire substrate was heated and held at 300°C, and the thickness was 500 mm.
A 30Ni-17Fe alloy thin film was formed by sputtering. Next, a sensor pattern similar to Manufacturing Example 1 was formed using a photoresist as an etching mask and a cupric chloride-based etching solution. Next, a 2 μm thick s+o2 film was deposited on the entire surface of the substrate by sputtering. Next, in order to form a terminal electrode, a window is opened at the required part, an Au film is laminated on the opened part, and an element pellet having a cross-sectional structure as shown in Fig. 4 is placed on a 3-inch square substrate. To,
It was formed during the approximately 2000 survey.

This board was cut into 1.2mm xl with a dicing saw.
It was cut into 8+nm device chips. After each element chip and the lead were connected by wire bonding, the terminal portion was molded with epoxy resin. Table 3 shows the characteristics of the obtained device. Resistance values and sensitivities equivalent to those of Production Example 1 were obtained.

Table 3 Manufacturing Example 4 An alumina ceramic substrate having a height of 0.1 mm and a protrusion of 1 mm x 1.5 mm square was pressed with a mold,
Formed by sintering. Next, S is applied to the entire surface of the board by PCVD.
t.2 film was deposited to a thickness of 3 μm, and the surface roughness of the protrusion forming the sensor portion was set to 100 Å or less. Next, the entire substrate was heated and maintained at 300°C, and a 83-17-100-100-100-100-100-100-100-100% polyester resin was heated to a thickness of 500 mm.
A JFe alloy thin film was formed by sputtering. Thereafter, the magnetoresistive element of the present invention was manufactured in the same manner as in Manufacturing Example 3.

The characteristics of the obtained device were similar to those of the device shown in Production Example 3.

[Effects of the Invention] As described above, according to the present invention, an element having a chip size of about 173 that is conventional can be manufactured.

In addition, it is possible to manufacture an element with a structure in which the terminal mold does not protrude from the sensor surface, and the gap between the sensor surface and the magnetic signal source can be set arbitrarily, so the signal magnetic field strength can be reduced as the signal source pitch becomes finer. It can fully cope with the decline. Further, unlike in the conventional case, there is no need to place the molded protrusion of the terminal section below the magnetic signal source, so the device can be made smaller, and the motor can also be made thinner and smaller.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, in which FIG. 1A is a top view of an element pellet, FIG. 1B is a sectional view taken along line 8 in FIG. The figure is a sectional view of an element structure showing an embodiment of the present invention in the case of solder bonding. Figure 3 is a sectional view of an element structure showing an embodiment of the invention in the case of wire bonding. Figure 4 is a device structure showing a second embodiment. A sectional view of the pellet, FIG. 5 is a layout diagram of the element of the present invention in a ring-shaped magnetic signal source, FIG. 6 is a process diagram showing an embodiment of the method for manufacturing the magnetoresistive element of the present invention, and FIGS. 7 (8) and ( B) is a top view of the magnetoresistive element in each step, FIGS. 8(A) and (B) are cross-sectional views taken along the line T and B in FIGS. 7(A) and (B), respectively, and FIG. 9 is a conventional Figure (A) shows a top view, Figure 111 is a cross-sectional view along A-At and !11 in Figure (8), and Figures 1θ and 11 are ring-shaped, respectively. It is a diagram showing an example of the arrangement of conventional elements in a magnetic signal source. 1.10... Insulating substrate, 2... Baked film, 3... Ferromagnetic thin film, 4.48, 4B, 4C... Terminal portion, 5... Protective film, 11... Ring-shaped magnetic signal source, 12... Element of the present invention, 13.15... Conventional element. ri's] two sides b ro t te J hi ° W 沓= ε] Fig. 1 large position 2 p 巳 koi 3 ``Summer con σa-''iff 圀弗图ification f) x te K I row/) stop乍面子 4th design ＼ い い Ｇ Ｇ Ｇ ＧＥ／） 蓓控 明京 千 ０ Ｇ １ fig.
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Claims (1)

[Claims] 1) In a magnetoresistive element that uses a thin film of ferromagnetic material as a magnetic sensor part, the sensor part made of the thin film is
A magnetoresistive element characterized by protruding from other parts of a pellet constituting the element. 2) A method for manufacturing a magnetoresistive element, comprising the step of depositing a ferromagnetic thin film on an insulating substrate having one or more protrusions with a height of at least 20 μm. 3) A method for manufacturing a magnetoresistive element, comprising the step of forming a protrusion made of an insulating material and having a height of at least 20 μm on a part of an insulating substrate by firing or fusing. 4) A method for manufacturing a magnetoresistive element, comprising the step of molding a substrate having a protrusion with a height of at least 20 μm using a mold. 5) By mechanical processing means, the height is at least 20μ
1. A method for manufacturing a magnetoresistive element, the method comprising the step of forming a substrate having m protrusions.